I just checked a bunch of 3-Arm cranksets for interchangeability.
All are 116 BCD and, surprisingly, all have 9.2 ~ 9.4 mm holes for 9mm diameter chainring bolts.
* TA Pro 3 * Nervar * Campagnolo steel GS * Stronglight steel (threaded with 9mm lip for chainring)
* Stronglight Aluminum rings * Cyclo Steel Rings
I may be mistaken, but all the classic 5-arm cranks I know have 10mm Dia chainring bolts.
Funny, the distinction.
Amir Avitzur
Ramat-Gan, Israel